A "serious and substantial morale problem" afflicts the nation's 53,500 Roman Catholic priests, many of whom are overworked, lonely and sexually troubled, says a groundbreaking report by a panel of U.S. bishops.

Discussing openly problems that once were kept quiet, the Bishops' Committee on Priestly Life and Ministry said some priests are just going through the motions, and many "have settled for a part-time presence to their priesthood."Part of the priests' morale problem, said the committee of the National Conference of Catholic Bishops, comes from the feeling that they are caught between Vatican directives and a Catholic laity that is often at odds with Rome.

Pope John Paul II has urged priests to accept suffering as part of their fate, but the American bishops have said that is not helpful and have compiled suggestions on how to improve priests' morale.

The panel report, obtained Friday by The Associated Press, said there are many creative and energetic priests, but "it is also clear to us that there exists today a serious and substantial morale problem among priests in general."

The report was hailed by Catholic clerics as the first official recognition of the situation's gravity.

"I think it's very encouraging that the bishops are helping the priests name the pain," said the Rev. Frank J. McNulty, who represented U.S. priests before the pope last year in Miami. "They're putting in this document what we've said ourselves over a cup of coffee. And that's a great help when you're trying to solve a problem."

Bishop John McRaith of the Owensboro, Ky., diocese, led the subcommittee that drafted the report. It was written for the nation's 300 bishops only, but church leaders decided in November to distribute it to priests.

"There really has been no scientific analysis done of the morale of priests," McRaith said Saturday. "I think our point was that the morale of priests always needs attention."

The shortage of priests is both a cause and a result of the morale problem, according to the report. A recent study by the Hartford Seminary's Center for Social and Religious Research said the number of Catholic seminarians declined from 8,885 in 1965 to 4,063 in 1985, and estimated that the number of priests will decline 40 percent by the year 2000. About 15 percent of priests have left the priesthood since 1970, said Dean R. Hoge, a sociologist at Catholic University of America.

Mandatory celibacy is a major reason for clergy leaving the priesthood and for loneliness among those who stay, the bishops said.